<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .css {
            margin: 0 auto;
            display: flex;
            width: 500px;
            height: 500px;
            background-color: aqua;
            /* 排序格式  row默认从左到右  row-reverse翻转 */
            flex-direction: row-reverse;
            justify-content: center;
            align-items: center;
            flex-wrap: wrap;
            align-content: space-between;
        }
        
        .s1 {
            background-color: seashell;
            width: 100px;
            height: 100px;
        }
        
        .s2 {
            background-color: red;
            width: 100px;
            height: 100px;
        }
        
        .s3 {
            background-color: salmon;
            width: 100px;
            height: 100px;
        }
    </style>


</head>

<body>

	

    <div class="css">
        <div class="s1"></div>
        <div class="s2"></div>
        <div class="s3"></div>
        <div class="s1"></div>
        <div class="s1"></div>
        <div class="s1"></div>
        <div class="s1"></div>
        <div class="s1"></div>
        <div class="s1"></div>
    </div>
    <strong>adwadaw</strong>

</body>

</html>